Investigating the antiproliferative activity of quinoline-5,8-diones and styrylquinolinecarboxylic acids on tumor cell lines

Article abstract of DOI:10.1016/j.bmcl.2007.09.040

The structure-activity relationships of new quinoline based compounds were investigated. Quinoline-5,8-dione and styrylquinoline scaffolds were used for the design of potentially active compounds. The novel analogues had comparable antiproliferative activ

Full text of DOI:10.1016/j.bmcl.2007.09.040

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry Letters 17 (2007) 6138–6141
Investigating the antiproliferative activity of quinoline-5,8-diones
and styrylquinolinecarboxylic acids on tumor cell lines
a
a
a,
a
a
a
a
*
B. Podeszwa, H. Niedbala, J. Polanski, R. Musiol, D. Tabak, J. Finster, K. Serafin,
b
b
c
c
d,e
d,e
M. Milczarek, J. Wietrzyk, S. Boryczka, W. Mol, J. Jampilek, J. Dohnal,
f
f
D. S. Kalinowski and D. R. Richardson
a
Department of Organic Chemistry, Institute of Chemistry, University of Silesia, PL-40006 Katowice, Poland
b
Department of Experimental Oncology, Ludwik Hirszfeld, Institute of Immunology and Experimental Therapy,
Polish Academy of Sciences, PL-53114 Wroclaw, Poland
c
Department of Organic Chemistry, Medical University of Silesia, PL-41200 Sosnowiec, Poland
d
Zentiva a.s., CZ-10237 Prague 10, Czech Republic
e
Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences,
CZ-61242 Brno, Czech Republic
Department of Pathology, Iron Metabolism and Chelation Program, University of Sydney, Sydney, New South Wales 2006, Australia
f
Received 25 July 2007; revised 7 September 2007; accepted 8 September 2007
Available online 14 September 2007
Abstract—The structure–activity relationships of new quinoline based compounds were investigated. Quinoline-5,8-dione and sty-
rylquinoline scaffolds were used for the design of potentially active compounds. The novel analogues had comparable antiprolifer-
ative activity to cisplatin when evaluated in a bioassay against the P388 leukemia cell line. However, these compounds appeared far
less efficient against SK-N-MC neuroepithelioma cells. Analogues without the 5,8-dione structure but containing the 8-carboxylic
acid group were also found to induce antiproliferative activity. Hydrophobicity as measured by HPLC did not correlate with anti-
proliferative activity.
Ó 2007 Elsevier Ltd. All rights reserved.
Quinoline-5,8-dione is a substantial molecular fragment
of lavendamycin (1) and related compounds (2, 3). Lav-
endamycin was originally isolated from the fermented
broth of Streptomyces lavendulae and this class of com-
pounds were identified in the 1970s as anti-tumor
ses of a series of quinoline-5,8-diones and lavendamycin
derivatives have been described. The evaluation of their
antiproliferative activity against transformed cells and a
normal rat kidney epithelial cell line validates their
3
importance as potential anti-tumor agents. In the cur-
1
agents.
rent study, we investigated the potential anti-tumor
activity of several known and novel quinoline-5,8-dione
analogues and derivatives.
The efficient synthesis of compound 2 made a number of
analogues available and revealed interesting biological
2
–5
activity. Their antiproliferative effects on cancer cells,
,7
As reported recently, structural modification of lavenda-
mycin to quinoline-5,8-diones having H or Me substitu-
tions at position 2 retains high cytotoxicity. However,
the resulting drugs are unselective and do not differenti-
ate between tumor and normal cells, making their phar-
maceutical use as anti-cancer agents problematic. On the
other hand, the unmodified lavendamycin molecule
showed improved selectivity against cancer cells. The
highest selective toxicity being observed for analogues
having a carboxylic acid group or its derivative at the
6
including leukemia cells and A549 carcinoma cells,
8
have been reported.
Although the toxicity of lavendamycin makes it unsuit-
able for clinical use, the activity of this compound has
9
–12
inspired several investigations.
Recently, the synthe-
Keywords: Antiproliferative activity; Quinoline-5,8-diones; Quinoline-
carboxylic acid.
0
C-2 position (see 1, 2 in Fig. 1).
3
*
Corresponding author. E-mail: Polanski@us.edu.pl
0
960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.09.040

B. Podeszwa et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6138–6141
6139
O
O
O
O
MeO
H N
MeO
N
COOH
N
N
O
N
COOH
CH3
2
H N
N
H
2
N
N
2
O
H N
CH3
2
O
H
N
CH
OH
N
2
3
OH
OMe
1
3
OMe
2
OMe
OMe
Figure 1. Structures of: lavendamycin (1), streptonigrin (2), and streptonigrone (3). In bold, the 7-aminoquinoline-5,8-dione moiety is shown.
In the current investigation, we examined the antiprolif-
erative activity of a series of quinoline-5,8-diones against
the mouse leukemia P388 line and human SK-N-MC
cancer cell type. This includes both the analogues previ-
ously described and novel compounds 7, 9 and 10.
Moreover, the effectiveness of the carboxylic substitu-
tion within the non-quinoline moiety of lavendamycin
inspired us to investigate the importance of the carbox-
ylic substitution by itself. Therefore, we synthesized a
series of quinoline analogues 12–32 having carboxylic
substitution(s) in the carbocyclic ring.
Results are shown in Table 1. The clinically used cyto-
toxic agent, cisplatin, was used as a reference compound
in this examination. Generally, the antiproliferative
activity of the quinolinediones on P388 cells (Table 1,
compounds 6–10) was similar to that of cisplatin. The le-
vel of antiproliferative activity of compounds 6–10
against P388 cells was similar, irrespective of the individ-
ual 7-R(CO)N-substitution pattern. The N-unsubstitut-
ed compound 4 was also an efficient cytotoxic agent,
although the activity of this compound was lower. It is
noteworthy that the 7-methoxy substitution in
compound 5 preserves the activity of analogue 4. This
indicates that although the 7-amido substitution
(compounds 6–10) is necessary for high cytotoxicity,
the potent activity of the quinolinedione scaffold is not
limited to the 7-amine substitution. The antiproliferative
activity of the two quinoline-5,8-dione compounds, 5
and 6, tested against SK-N-MC cells, was far less potent
than that seen in P388.
As shown in Figure 2, quinolines containing the carbox-
ylic group were obtained according to Skraup protocol
from appropriate aminobenzoic acids. Styrylquinolines
were synthesized from 8-hydroxyquinaldine or quinaldic
acids by the Skraup reaction, employing a microwave-
1
3,14
assisted protocol.
Multi-step reactions lead us to 4
and 5. Acylation with appropriate chlorides afforded
amides 6–10.
We investigated if further modification of the quinoline
scaffold by the removal of the 5,8-quinone function
would retain activity. Therefore, 8-hydroxy-5,7-dinitro-
quinoline 11 was obtained. The presence of the nitro-
The antiproliferative activity of the synthesized com-
pounds was tested against the P388 mouse leukemia
and SK-N-MC human neuroblastoma cell lines.
1
5
a
b
1
R
1
1
R
R
NH2
N
N
2
R
12-15, 17, 19-27
b
1
R
N
N
2
R
OH
16, 18, 28-32
c
O
O
O
O
O
d
e
O
MeO
N
R
N
N
H N
N
2
O
4
6-10
5
1
3
2
Figure 2. (a) Skraup synthesis, crotonaldehyde; (b) microwave irradiation and aromatic aldehyde; (c) multi-step synthesis described earlier ;
d) MeOH; (e) Py/acid chlorides.
(

6140
B. Podeszwa et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6138–6141
Table 1. LogK determinations using HPLC and antiproliferative activity assay results of the compounds examined in this study
a
Compound
LogK
Antiproliferative activity
O
P388
SK-N-MC
O
R
N
N
H
O
R
IC50 ðlMÞ
IC50 ðlMÞ
ND
4
5
6
7
8
9
See Figure 2
See Figure 2
CH3–
ND
10:31 ꢀ 6:80
6:10 ꢀ 2:80
1:61 ꢀ 0:87
1:43 ꢀ 1:06
1:51 ꢀ 0:85
1:44 ꢀ 0:28
2:39 ꢀ 0:34
0.0907
0.2227
ND
4.26
> 6:25
ND
CH3CH2–
CH3CH2CH2–
PhCH2CH2–
ðEÞ-PhCH@CH–
ND
ND
ND
ND
10
ND
ND
NO2
11
0.7154
7:14 ꢀ 3:78
> 6:25
O N
N
2
OH
1
R
N
2
R
1
2
R
R
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
8-COOH
2-OH
2-Cl
4-Cl
1.6787
1.2047
1.2107
1.2163
ND
13:56 ꢀ 1:24
113:72 ꢀ 14:70
109:68 ꢀ 10:54
113:81 ꢀ 32:42
79:11 ꢀ 10:64
116:29 ꢀ 46:91
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
5,8-COOH
5,8-COOH
5,8-COOH
3-Cl
5,7-NO2-8-OH
6-COOH
8-OH
4-OMe
4-Cl
3-Cl
1.6043
1.5395
1.3842
1.2062
1.2263
1.8165
1.6315
1.2550
1.1811
1.4397
1.3678
ND
b
15
6-COOH
5,8-COOH
5-COOH
8-COOH
6-COOH
5-COOH
5,8-COOH
5-COOH
7-COOH
5,7-NO2-8-OH
2-OH
2-Br
51:15 ꢀ 31:44
89:40 ꢀ 30:43
100:02 ꢀ 24:3
15:33 ꢀ 1:26
3-OMe
4-Cl
3-Cl
109:77 ꢀ 53:91
b
2-OH
3-OMe
4-Br
30
b
25
109:12 ꢀ 18:21
b
2-OH
4-Cl
30
c
7:14 ꢀ 3:78
b
20
5,7-NHAc-8-OAc
5-NO2-7-COOH-8-OH
5-NO2-7-COOH-8-OH
5,7-NHAc-8-OAc
cisplatin
2,4-OMe
2-Cl
ND
ND
158:38 ꢀ 45:53
147:63 ꢀ 49:44
6:58 ꢀ 4:43
4-OMe
2-Br
ND
ND
3:39 ꢀ 1:54
The results are means ± standard deviation of 3–7 experiments. ND, not determined.
a
Compounds 4–6 and 11 were described previously in Ref. 2, compound 8 in Ref. 4, compounds 12, 15, 16, 18, 19, 21, 24, 27 in Ref. 3, 28, 29, 31 in
Ref. 16, 23 in Ref. 17.
b
c
Antiproliferative activity could be measured only as percent of inhibition of cancer cells proliferation at 0.1 lM.
Under poor solubility in the test medium.
substituents makes the 8-hydroxy group highly acidic
vidual structure of the amide group. It is of interest to
note that there is a marked difference in the antiprolifer-
ative activity of compounds 5, 6, and 11 when compar-
ing P388 leukemia cells and the SK-N-MC
neuroepithelioma line. Similarly to compound 6, ana-
logue 11 showed very limited activity against the SK-
N-MC line, while compound 5 was active against both
line types.
which should mimic the 8-quinolinone structure. In fact,
it appeared that this compound was an efficient antipro-
liferative agent against P388 cells, having activity similar
to that of the unsubstituted 7-aminequinaldine-5,8-
dione (compound 4). The SAR observed in compounds
6–10 indicated that the cytotoxic activity of these ana-
logues depended only to a limited extent upon the indi-

B. Podeszwa et al. / Bioorg. Med. Chem. Lett. 17 (2007) 6138–6141
6141
In the styrylquinoline series (compounds 12–32), some
interesting relationships between structural properties
and P388 cell line activity were observed. Compound 28
having the 8-OH function of the acidity enhanced by
3. Behforouz, M.; Cai, W.; Mohammadi, F.; Stocksdale, M.
G.; Gu, Zh.; Ahmadian, M.; Baty, D. E.; Etling, M. R.;
Al-Anzi, Ch. H.; Swiftney, T. M.; Tanzer, L. R.; Merri-
man, R. L.; Behforouz, N. C. Bioorg. Med. Chem. 2007,
1
5, 495.
5
,7-dinitro substitution showed the activity similar to that
4
. Behforouz, M.; Cai, W.; Stocksdale, M. G.; Lucas, J. S.;
Jung, J. Y.; Briere, D.; Wang, A.; Katen, K. S.; Behfo-
rouz, N. C. J. Med. Chem. 2003, 46, 5773.
of compounds 4 and 11, which can be probably explained
by the effect similar to that discussed for compound 11.
5
. Behforouz, M.; Gu, Z.; Cai, W.; Horn, M. A.; Ahmadian,
M. J. Org. Chem. 1993, 58, 7089.
6. Balitz, D. M.; Bush, J. A.; Bradner, W. T.; Doyle, T. W.;
The carboxylic group located at the C-8 position was
found to induce antiproliferative effects, as observed in
compounds 12 and 22. If we compare the activity of
compounds 12 and 22 to the high activity of compound
O’Herron, F. A.; Nettleton, D. E. J. Antibiot. (Tokyo)
1
982, 35, 259.
. Abe, N.; Nakakita, Y.; Nakamura, T.; Enoki, N.; Uchida,
7
8
9
1
1, where the 8-hydroxy group mimics the C@O
H.; Takeo, S.; Munekata, M. J. Antibiot. (Tokyo) 1993,
46, 1672.
. Fang, Y.; Linardic, C. M.; Richardson, D. A.; Cai, W.;
Behforouz, M.; Abraham, R. T. Mol. Cancer Ther. 2003,
2, 517.
. Doyle, T. W.; Balitz, D. M.; Grulich, R. E.; Nettleton, D.
E.; Gould, S. J.; Tann, C.-H.; Meows, A. E. Tetrahedron
Lett. 1981, 22, 4595.
10. Hackethal, C. A.; Golbey, R. B.; Tan, C. T. C.; Karnof-
sky, D. A.; Burchenal, J. H. Antibiot. Chemother. 1961, 11,
through nitro substitution, the antiproliferative efficacy
was probably due to the close proximity of the C@O
and the heterocyclic nitrogen. This explanation is
thought to be more probable to explain the activity
rather than implicating the ionizable properties of the
8-COOH group. This feature is reminiscent of the origi-
nal lavendamycin 1 structure, featuring a carbonyl with
a neighboring heterocyclic nitrogen.
1
78.
1. Boger, D. L.; Yasuda, M.; Mitscher, L. A.; Drake, S. D.;
On the other hand, the CO/N proximity rule was no
longer true if an additional COOH group was present
within the quinoline moiety, e.g., the activity of com-
pounds 13–15 was much lower than that observed for
compound 12 or the activity of compounds 30 and 31
was much lower than that observed for 22.
1
Kitos, P. A.; Thompson, S. C. J. Med. Chem. 1987, 30,
1
918.
2. Wilson, W. L.; Labra, C.; Barrist, E. Antibiot. Chemother.
961, 11, 147.
1
1
1
3. Musiol, R.; Podeszwa, B.; Finster, J.; Niedbala, H.;
Polanski, J. Monatsh. Chem. 2006, 137, 1211.
The same effect was observed for all compounds having
the COOH substitution accompanied by an additional
electroaccepting group. Thus, compound 32 having high
activity (CO/N proximity can be here identified by the het-
erocyclic N and 8-O(CO)Me substitution) can be com-
pared to low activity compounds 30–31 which have an
additional 5-COOH/7-NO system. Since such a substitu-
2
tion increases the ionization of COOH, this suggests that
this effect is disadvantageous for antiproliferative activity.
14. Musiol, R.; Jampilek, J.; Kralova, K.; Richardson, D. R.;
Kalinowski, D. S.; Podeszwa, B.; Finster, J.; Niedbala, H.;
Palka, A.; Polanski, J. Bioorg. Med. Chem. 2007, 15, 1280.
1
5. The mouse P388 leukemia cell line and human SK-N-MC
neuroepithelioma cell type were obtained from the Amer-
ican Type Culture Collection (Rockville, MD, U.S.A.).
The P388 cell line was cultured in RPMI 1640 medium
with 2 mM L-glutamine adjusted to contain 1.5 g/L
sodium bicarbonate, 4.5 g/L glucose, and 1.0 mM sodium
pyruvate, 10% fetal bovine serum (FBS) at 37 °C in 5%
CO2. The SK-N-MC cell type was cultured in minimum
essential medium (MEM; Gibco, Melbourne Australia)
containing 10% (v/v) FBS, 1.0 mM sodium pyruvate
The attempt to explain the antiproliferative activity of this
series of compounds by hydrophobicity measured by
HPLC (column 3, Table 1) was unsuccessful. This param-
eter did not closely correlate with antiproliferative activity.
(
2
Gibco), 1% (v/v) non-essential amino acids (Gibco),
mM L-glutamine (Gibco), 100 U/mL penicillin (Gibco),
streptomycin (Gibco), and 0.28 lg/mL fungizone (Squibb
Pharmaceuticals, Montreal, Canada). Twenty-four hours
before addition of the tested compounds, the cells were
plated in 96-well plates. The assay was performed after
Acknowledgments
7
2 h exposure to varying concentrations of the tested
This study has been supported by Polish Ministry of Sci-
ence Grant No. 3T09A 01127 and by the Ministry of
Education of the Czech Republic MSM 6215712403.
D.R.R. thanks the National Health and Medical Re-
search Council (NHMRC) of Australia for Fellowship
and Project Grant funding and the Australian Research
Council (ARC) for a Discovery Grant. D.S.K. appreci-
ates the support of an Australian Post-Graduate Award.
agents. The results were calculated as IC50 values. Each
concentration of each individual compound was tested in
triplicate in a single experiment, with each experiment
being repeated 3–7 times. After 72 h of incubation with
tested compounds, 20 lL of MTT solution (MTT: stock
solution: 5 mg/mL) was added to each well and incubated
for 4 h at 37 °C. After this incubation, 80 lL of the lysis
mixture was added to each well (lysis mixture: 225 mL
dimethylformamide, 67.5 g sodium dodecyl sulphate, and
275 mL of distilled water). The optical densities of the
samples were read after an incubation of 24 h at 570 nm.
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